Figure 1. The procedure of ligating two DNA fragments via overlap extension PCR.

The first fragment is shown with a long blue arrow (sense strand) and a long orange arrow (antisense strand). The second fragment is shown with a long cyan arrow (sense strand) and a long purple arrow (antisense strand). The arrows show the 5′–3′ direction of DNA. The PCR#1 shows the amplification of the upstream fragment with primer gene_5 and primer overlap_3. The PCR#2 shows the amplification of the downstream fragment with primer overlap_5 and primer gene_3. The upstream and downstream fragments bridge within the overlapping region during the overlap PCR of the full-length chimera sequence.